1. Field of the Invention
The present invention generally relates to image enhancement, and more particularly to depth-based image or video enhancement.
2. Description of the Prior Art
When three-dimensional (3D) objects are mapped onto a two-dimensional (2D) image plane by prospective projection, such as an image taken by a still camera or video captured by a video camera, a lot of information, such as the 3D depth information, disappears because of this non-unique many-to-one transformation. That is, an image point cannot uniquely determine its depth. Recapture or generation of the 3D depth information is thus a challenging task that is crucial in recovering a full, or at least an approximate, 3D representation, which may be used in image enhancement, image restoration or image synthesis, and ultimately in image display.
Image enhancement is an important aspect in the processing of both digital image and video information. To a large extent, image enhancement is applied in nearly all digital image processing tasks. In one hand, the image enhancement is utilized to improve the image quality, such as the contrast and the brightness. On the other hand, the image enhancement is utilized to prepare or preprocess an image for subsequent image processing.
Image edge enhancement or detection is one of the important image enhancement operations. Typical image edge enhancement emphasizes and shows the edge details of an image, such as the outlines of objects within the image, while retaining or even suppressing other portions of the image.
Two-dimensional (2D) frequency transform is conventionally applied to a 2D image that is to be edge-enhanced. The frequency transform converts an image from a spatial-domain representation of brightness into a frequency-domain representation of frequency components. The magnitude of the high-frequency component(s), or the edge information, of the frequency-transformed image is then increased or enhanced, resulting in an edge-enhanced image. This method disadvantageously gives little consideration to the distinct depth information among different edges. Accordingly, the respective edges are monotonously assigned the same depth value.
For reasons including the that conventional methods could not faithfully enhance an image, a need has arisen to propose a system and method of depth-based image/video enhancement that can enhance an image while considering respective 3D depth information.